What does Paul mean in Galatians 5:2 by 'if ye be circumcised'?

Les teaches that the admonition is to Galatian believers not to fall victim to legalizers making inroads into the congregations Paul established in Asia Minor. Paul writes in Galatians 5:1, "Stand fast therefore in the liberty wherewith Christ hath made us free, be not entangled again with the yoke of bondage," which is legalism, the law, Judaism. Then verse 2 says, "Behold, I, Paul, say unto you, that if ye be circumcised." Les explains this is talking about salvation. If they depend on something they can do in the flesh for their salvation, then "Christ shall profit you" nothing. Les says this shook him up and scared him, because millions of good people, church members, who would not miss a Sunday morning service, are depending on something of the flesh they have done rather than relying totally on the finished work of the cross. This is any one thing plus the cross; you cancel the work of the cross. He warns that if you be circumcised, if you do anything in the energy of the flesh, Christ shall profit you nothing.